There are 2+3+5+3 = 13 leaves total. This represents tickets were sold on 13 days.
Each stem and leaf combines to form a different ticket count. For instance, the stem of 1 and leaf of 8 combine to get the value 18. So 18 tickets were sold on that particular day.
If you look at the coordinate plane, you'll notice that the x -values are negative and the y-values are positive. So, if you look at where the two lines meet, they meet at the point (-2,3).
